1. Field of the Invention
This invention relates generally to medical electrode systems and, in particular, to a defibrillator electrode system for use with an automatic or semi-automatic external defibrillator (AED).
2. Description of the Prior Art
One frequent consequence of heart attacks is the development of cardiac arrest associated with heart arrhythmias, such as ventricular fibrillation. This abnormal heart rhythm is caused by an abnormal and very fast electrical activity in the heart. During ventricular fibrillation the heart cannot pump blood effectively. Ventricular fibrillation may be treated by applying an electric shock to the patient's heart through the use of a defibrillator. Defibrillation clears the heart of the abnormal electrical activity and allow the heart's natural pacemaker areas to restore normal function. Because blood is no longer pumping effectively during ventricular fibrillation, the chances of surviving a heart attack decreases with time after the attack. Quick response to a heart attack by administering a defibrillating shock as soon as possible after the onset of ventricular fibrillation is therefore often critically important.
Increasing the number of potential defibrillator operators who are trained on the proper use of an external defibrillator increases the likelihood that a trained defibrillator operator will be available during an emergency and thus could ultimately reduce the defibrillator deployment time. As the number of potential operators increases, however, the frequency with which each operator uses the skills developed during training decreases. Depending upon the amount of time since the defibrillator operator last used a defibrillator, review of electrode placement instructions will likely be required to determine correct placement of the electrode pads since failure to apply the electrode pads correctly can reduce the amount of energy that is applied to the heart and may result in a failure of the defibrillation shock. Such a review, while necessary, delays the speed with which defibrillation can be performed on the patient. With every second that passes, the likelihood of successfully restoring the patient's heart to a normal sinus rhythm decreases. Therefore, every step in the deployment and use of a defibrillator that can be streamlined is critical.
One time saving gain has been the development of electrode pads which eliminate the step of attaching the electrode pads to the cable, and, for the most part, eliminate the need to untangle the cable. An example of such an electrode system is described in U.S. Pat. No. 5,466,244 for "Defibrillator Electrode System" by Morgan. Other electrode pads have also been developed that attempt to decrease the amount of time a defibrillator operator spends deploying the electrode pads.
R2 Medical Systems has developed a multi-function electrode system, R2.RTM. PADS.TM., that features two circular electrode pads. Each electrode pad has its own release liner. One electrode pad, approximately 12.5 cm in diameter, is attached to a blue lead line that is integral with the defibrillator connector. A blue label with white writing on this electrode pad reads: ##EQU1## The second electrode pad, that is noticeably larger at approximately 17 cm in diameter, is attached to a white lead line which is also integral with the same connector. A white label with blue writing on the electrode pad reads: ##EQU2## A more detailed description of the electrode pad system can be found in U.S. Pat. Nos. 4,483,103, 4,852,858, 4,895,169, 4,419,998 and 4,653,503 (Heath). The size differences, lead line coloration, and markings would not assist a defibrillator operator with the correct placement of the electrode pads in an emergency situation, particularly if the operator had not been recently trained or recently used an AED. It is likely that a defibrillator operator would need to return to the packaging to determine how to properly place the electrode pads, taking up precious additional time.
Physio-Control Corporation has developed yet another approach, the QUIK-COMBO.TM. electrode system also featuring two electrode pads. Both electrode pads are the same size and attached to black lead lines that are integral with a defibrillator connector. Each electrode pad also has its own separate release liner. The first electrode pad has a first label identifying the electrode pad as a QUIK-COMBO.TM. electrode with a second label imprinted with a red heart attached to the electrode pad where the lead wire from the connector attaches to the electrode pad. The second electrode pad has a first label with a picture depicting the placement of the electrode pads, showing an image of human torso with one electrode pad with a red heart on the lower left side of a torso, and an image of a second electrode pad with no such marking on the upper right. The second electrode pad also has a second label with no markings covering the area where the lead wire from the connector attaches to the electrode pad. The packaging for the electrode pads shows two alternate placement strategies, but warns that the second placement strategy should not be used with AEDs. Failure to either be familiar with the electrode pad system, or to closely read the packaging could result in an incorrect placement of the electrode pads.
Zoll Medical Corporation has developed the STAT PADZ.TM. multi-function electrode system again featuring two electrode pads. The Zoll electrode pads are each attached to lead wires that are integral with the defibrillator connector. Each electrode pad is attached to a sheet of plastic that is adhered to the interior surface of the product's packaging such that when the packaging is correctly opened along its three seams, the pads will lie exposed on what had been the interior surface of the packaging. When the packaging is sealed after manufacturing for shipping, the upper surfaces of each electrode pad are in contact until the packaging is finally opened. The lower (adhesive) surface of the electrode pads, are, as described above, attached to the plastic liner, which in turn is securely adhered to the interior surface of the product's packaging. The electrode pads are oriented on the interior surface of the packaging so that one lead line is oriented toward the top opening of the packaging while the other lead line is oriented toward the sealed bottom of the packaging. This orientation of the electrode pads results in top-to-bottom orientation of the electrodes and the labeling (described below) once the packaging is opened.
The Zoll first electrode pad is round with two labels. The first label identifies the electrode pad as a "Zoll STAT PADZ". The second label on the first electrode pad depicts the front of a human torso with a round electrode on the lower left side of the ribs. Additionally, the wording on the label indicates "FRONT (Apex) PACE/DEFIB". The second electrode pad is square and also features two labels. Again, the first label on the second electrode pad identifies the electrode pad as a "Zoll STAT PADZ". The second label on the second electrode pad depicts of the back of a human torso with a square electrode on the left side of the spine covering a portion of the shoulder. Additionally the label includes the wording "BACK PACE/DEFIB". The packaging pictures a front torso and a rear torso with the electrode pads positioned thereon.
Cardiotronics has taken another approach with their MULTI-PADS.TM. electrode pad product. The Cardiotronics electrode pads are the same size, and each is attached to a lead wire that is integral with a defibrillator connector. One electrode pad is labeled "RA" and the second electrode is labeled "APEX". A picture on the packaging shows the correct placement of the "RA" and "APEX" electrode pads. A more detailed explanation of the Cardiotronics electrode pads is found in U.S. Pat. No. 5,080,099 (Way et al.).
U.S. Pat. No. 5,330,526 (Fincke et al.) describes a combined defibrillation and pacing electrode that features a round electrode pad for placement on the chest area of a patient's thorax, and a second rectangular electrode pad for alignment with the spine on the back are of the patient's thorax. According to Fincke et al., the shapes allow for easy placement of the electrode pads in their respective sites on the patient's thorax.
What is needed is a quick and easy to use electrode system which clearly shows the defibrillator operator how to correctly place the electrode pads on a patient without requiring a review of the packaging. What is also needed is a way of marking the electrode pads so that the correct placement of each electrode pad is clear without requiring review of the second electrode pad or requiring extensive familiarity with the particular electrode brand. Ideally, what is needed is an electrode system that will enable an AED operator to deploy and the electrode pads correctly in a minimum amount of time, regardless of how often the operator is called upon to use his or her AED training.